KR100811487B1 - Ductless dryer - Google Patents

Abstract

A ductless dryer is provided to prevent damage to clothes by reducing gas amount which is flowed in gas combustor by controlling a gas valve. A ductless dryer comprises a body(110), a drum, a hot blast supplying unit(140), and a heat exchanging unit. The hot blast supplying unit supplies hot blast into the drum, and regulates heat to warm up air. The heat exchanging unit dehumidifies humid air which is discharge from the drum. The hot blast supplying unit has gas combustor, a gas valve(141), a hot blast supplying duct, and at least one hot blast temperature sensor. The gas combustor mixed gas with air and ignites the mixture of gas to generate hot blast. The gas valve supplies and cuts off gas which is supplying to the gas combustor. The hot blat supplying duct induces hot blast from the gas combustor to the drum. The hot blast temperature sensor measures temperature of hot blast flowed in the drum.

Description

Ductless Dryer {DUCTLESS DRYER}

1 is a schematic diagram of a ductless dryer according to an embodiment of the present invention,

2 is a plan view of the ductless dryer of FIG.

3 is a block diagram showing a first modification of the hot air supply unit of FIG.

4 is a block diagram illustrating a second modification of the hot air supply unit of FIG. 2;

5 is a graph showing the air temperature and the on-off cycle of the heater at the drum inlet when the heater capacity is 5400W,

6 is a graph showing the air temperature at the drum inlet and the on-off period of the heater when the heater capacity is 4600W;

7 is a graph showing the air temperature at the drum inlet and the on-off period of the heater when the heater capacity is 4150W;

8 is a chart comparing the drying performance according to the heater capacity,

9 is a view showing an extract of the heat exchanger of FIG.

10 is a graph showing the temperature and humidity of the humid air at the first and third points of FIG.

FIG. 11 is a graph comparing the dew point temperature of the wet air at the first point of FIG. 9 with the temperature of the water leaving the first heat exchanger.

<Explanation of symbols for the main parts of the drawings>

110: main body 111: door

113: foot 114: circular duct

120: drum 131: belt

133: fan 140, 170, 180: hot air supply

141: gas valve 143: gas burner

145: hot air supply duct 147: hot air temperature sensor

171: fixed heater 173: variable heater

181: first fixed heater 183: second fixed heater

185: third fixed heater 200: heat exchange unit

210; Case 220: first heat exchanger

230: second heat exchanger 253, 255, 247: air temperature sensor

254, 256, 258: humidity sensor

The present invention relates to a ductless dryer, and more particularly, to minimize the amount of water used for drying the object to be dried and dehumidifying the vented air, and frequently to stop the combustion of gas or to turn on the heater when the air volume in the dryer decreases. It relates to a ductless dryer which prevented (on / off).

In general, a clothes dryer is a device that blows hot air into a drum to absorb moisture in a drying object and to dry the drying object. The clothes dryer is largely exhausted according to a treatment method of wet air generated by absorbing moisture to dry the drying object. It is classified as a type clothes dryer and a condensation clothes dryer.

Exhaust type clothes dryer uses a method of exhausting the humid air discharged from the drum to the outside of the dryer. However, an exhaust duct for exhausting the vaporized water in the drum to the outside is required, and in particular, since the combustion product carbon monoxide and the like are exhausted, there is a disadvantage in that the exhaust duct must be extended to be installed outside.

On the other hand, the condensation type clothes dryer uses a method of condensing the humid air exhausted from the drum in the heat exchanger to remove moisture, and then sending dry air from which the moisture is removed back to the drum to recycle. However, there is a disadvantage that it is not easy to use gas as a heat source because dry flow forms a closed loop.

It is a ductless dryer that overcomes the disadvantages of the exhaust type clothes dryer and the condensation type clothes dryer, and the ductless dryer does not need to install the exhaust duct for exhausting the evaporated water in the drum to the outside and install the drum long. The condensed wet air is condensed in the heat exchanger to remove moisture, and then the dry air from which the moisture is removed is sent back to the drum so as not to be recycled.

However, such a ductless dryer heats the air flowing from the outside by a gas combustion or an electric heater and flows it into the drum in a high temperature dry state, where the amount of air in the dryer is reduced for various reasons to prevent damage to the fabric or fire. In a frequent case, the combustion of the gas is frequently stopped or the heater is turned on / off. This adversely affects the safety of the cloth or dryer.

In addition, the ductless dryer includes a heat exchanger for drying the object to be dried and for removing moisture contained in the exhausted air. The heat exchanger includes a fin and a tube passing between the fins, and condenses the wet air in contact with the fin by flowing water below the dew point temperature of the wet air in the tube to remove moisture. However, if water is lower than the dew point of wet air when supplying water to the tube, it is no longer necessary to flow water into the tube. do.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a ductless dryer which prevents frequent combustion of a gas or an on / off heater when the air volume in the dryer decreases. To provide.

In addition, another object is to provide a ductless dryer for controlling the amount of water used for dehumidification of the heat exchanger according to the dew point temperature of the humid air.

Ductless dryer according to the present invention for achieving the above object, the main body; A drum rotatably installed on the main body; A hot air supply unit for providing hot air into the drum and adjusting heat for heating the air according to the air volume; And a heat exchanger for dehumidifying the humid air exhausted from the drum.

In addition, the object is a main body; A drum rotatably installed on the main body; Hot air supply unit for providing hot air into the drum; And a heat exchanger for dehumidifying the humid air exhausted from the drum and adjusting the amount of water for dehumidifying the humid air according to the dew point temperature of the humid air.

In addition, the object is a main body; A drum rotatably installed on the main body; A hot air supply unit for providing hot air into the drum and adjusting heat for heating the air according to the air volume; And a heat exchanger for dehumidifying the humid air exhausted from the drum and adjusting the amount of water for dehumidifying the humid air according to the dew point temperature of the humid air.

Hereinafter, a ductless dryer according to an embodiment of the present invention will be described in detail.

1 is a schematic diagram of a ductless dryer according to an embodiment of the present invention, Figure 2 is a plan view of the ductless dryer of FIG. Arrows indicate the flow of air.

1 and 2, a ductless dryer according to an embodiment of the present invention includes a main body 110; A drum 120 rotatably installed in the main body 110; Hot air supply unit 140 to provide hot air into the drum 120, and to adjust the heat for heating the air according to the air volume; And a heat exchanger 200 for dehumidifying the humid air exhausted from the drum 120 and adjusting the amount of water for dehumidifying the humid air according to the dew point temperature of the humid air.

A door 111 for injecting clothes into the drum 120 is installed on the front surface of the main body 110, and a foot 113 for supporting the main body 110 is installed below the main body 110. Inside the main body 110, the belt 131 for rotating the drum 120 and the fan 133 installed in the circulation duct 114 for providing a blowing force of air in the ductless dryer and the belt 131 and the fan 133 A motor 135 providing a driving force is installed. The pulley 137 on which the belt 131 is caught is provided on the rotating shaft of the motor 135. Here, a plurality of motors 135 may be configured to provide driving force to the belt 131 and the fan 133, respectively. On the other hand, the circulation duct 114 is provided with a filter (not shown) for filtering lint (Lint), such as lint or seams contained in the air of high temperature and high humidity exiting from the drum 120.

The drum 120 is a barrel having an inner space to allow the clothes to be dried, etc. to be inserted therein, and a plurality of lifters 121 are installed therein to lift the clothes.

The hot air supply unit 140 is a gas valve 141 for supplying and blocking gas and a gas burner 143 for mixing the gas exhausted from the gas valve 141 with the air provided from the outside to ignite to generate hot air, The hot air supply duct 145 connecting the gas burner 143 and the drum 120 so that the generated hot air is supplied to the drum 120 and the hot air temperature sensor 147 measuring the temperature of the hot air flowing into the drum 120. It includes;

The hot air supply unit 140 may be provided with a flame rod extending to the edge of the flame to detect the flame current and indirectly determine the generation amount of carbon monoxide (CO) through the value of the flame current.

The gas combustor 143 is connected to the gas valve 141 and mixes and combusts the gas exhausted from the gas valve 141 and external air, and heats air with heat generated at this time. The hot air generated by heating is provided to the drum 120 through the hot air supply duct 145.

The hot air temperature sensor 147 is installed at the connection portion 145a of the hot air supply duct 145 and the drum 120. Of course, a plurality of hot air temperature sensor 147 may be used as needed, and may also be installed in the hot air supply duct 145.

The temperature value measured by the hot air temperature sensor 147 is when the air flow rate of the air flowing in the dryer decreases, for example, when lint is stuck in the filter to block the flow of air, there is too much foam in the drum so that the air flow is not desired. If the air volume in the dryer decreases due to a blockage of the duct connected to the outside, the temperature of the air flowing into the drum 120 may exceed the appropriate temperature range (temperature that is managed for cloth damage or fire) to damage the cloth. Given.

In order to prevent this, the hot air supply unit 140 adjusts the amount of gas supplied to the gas burner 143 by adjusting the gas valve 141 according to the air flow rate. That is, when the air volume decreases and the temperature value measured by the hot wind temperature sensor 147 exceeds an appropriate temperature range, the gas valve 141 may be locked in part or all to reduce the amount of gas flowing into the gas burner 143. Block it. To this end, the gas valve 141 preferably uses a solenoid valve so as to adjust the gas injection amount sensitively.

As a result, it is possible to lower the temperature of the air by reducing the amount of heat supplied to the air flowing into the drum 120 without frequently stopping the combustion of the gas. This can prevent damage to the cloth and improve the stability of the dryer.

3 is a block diagram illustrating a first modification of the hot air supply unit of FIG. 2, and FIG. 4 is a block diagram illustrating a second modification of the hot air supply unit of FIG. 2.

Referring to FIG. 3, the hot air supply unit 170 according to the first modification includes a fixed heater 171 and a variable heater 173.

The fixed heater 171 occupies 50% of the heater capacity and the variable heater 173 is adjusted to occupy 0 to 50% of the heater capacity. With the above-described configuration, the heater capacity is 100% when the temperature of the air flowing into the drum 120 (see FIG. 1) measured by the hot wind temperature sensor 147 (see FIG. 1) is in a normal range because there is no problem in the air volume. To be That is, the fixed heater 171 having a heater capacity of 50% is turned on, and the variable heater 173 is operated in full so that the heater capacity of the variable heater 173 is 50%.

However, when the air volume decreases and the temperature of the air flowing into the drum 120 (see FIG. 1) measured by the hot wind temperature sensor 147 (see FIG. 1) exceeds the normal range, the heater capacity is reduced. That is, the fixed heater 171 having a heater capacity of 50% is turned on and the heater capacity of the variable heater 173 is adjusted to be less than 50%. As a result, the supply amount of heat supplied to the air flowing into the drum 120 (see FIG. 1) is reduced, so that the temperature of the air is lowered to prevent damage to the cloth.

Here, the determination of the decrease in the amount of air flows is that the temperature of the air flowing into the drum 120 (see FIG. 1) measured by the hot wind temperature sensor 147 (see FIG. 1) reaches a preset maximum temperature value after starting drying. Use the time it takes to make a decision. In other words, the shorter the time, the less the air volume.

Referring to FIG. 4, the hot air supply unit 180 according to the second modification includes a plurality of fixed heaters.

In the present embodiment, the fixed heaters include a first fixed heater 181 having a heater capacity of 50%, a second fixed heater 183 having a heater capacity of 30%, and a third fixed heater 185 having a heater capacity of 20%. ).

With the above-described configuration, the heater capacity is 100 when the temperature of the air flowing into the drum 120 (see FIG. 1) measured by the hot wind temperature sensor 147 (see FIG. 1) is in the normal range because there is no problem in the air volume. To%. That is, all of the first fixed heater 181, the second fixed heater 183, and the third fixed heater 185 are turned on.

However, when the air volume decreases and the temperature of the air flowing into the drum 120 (see FIG. 1) measured by the hot wind temperature sensor 147 (see FIG. 1) exceeds the normal range, the heater capacity is reduced. That is, the first fixed heater 181, the second fixed heater 183, and the third fixed heater 185 or all of the part is turned on to adjust the heater capacity. As a result, the supply amount of heat supplied to the air flowing into the drum 120 (see FIG. 1) is reduced, so that the temperature of the air is lowered to prevent damage to the cloth.

Here, the determination of the decrease in the air volume is similar to the first modified example, in which the temperature of the air flowing into the drum 120 (see FIG. 1) measured from the hot air temperature sensor 147 (see FIG. 1) starts drying and the maximum value is set. Take time to reach the temperature value. That is, the shorter the time means that the air volume is reduced.

Hereinafter, when the heater capacity can be varied as in the first modification and the second modification, the on-off cycle and drying performance of the heater according to the heater capacity will be described.

5 is a graph showing the air temperature at the drum inlet and the on-off period of the heater when the heater capacity is 5400W, Figure 6 is a graph showing the air temperature at the drum inlet and the on-off period of the heater when the heater capacity is 4600W 7 is a graph showing the air temperature at the drum inlet and the on-off period of the heater when the heater capacity is 4150W, and FIG. 8 is a chart comparing drying performance according to the heater capacity.

5 to 7, the heater capacity is approximately on-off cycle is 3 minutes at 5400W and the temperature of the air is 225 ℃, the heater capacity is at 4150W approximately on-off cycle is approximately 10 minutes and the temperature of the air is 215 ℃. Therefore, as the heater capacity decreases, the maximum temperature range of the air flowing into the drum 120 (see FIG. 1) measured by the hot air temperature sensor 147 (see FIG. 1) is dropped by 10 to 20 ° C. or more, and the on / off cycle of the heater ( It can be seen that the length of ΔT) is long and the number of on / off decreases. However, the larger the capacity of the heater, the shorter the time to reach the maximum drying initial temperature (the time that the drying of the cloth is substantially active) is more advantageous to reduce the drying time.

Referring to FIG. 8, when the air volume in the dryer is insufficient, there is no performance reduction in drying time and power consumption, which are major indicators of drying performance, even if the heater capacity is reduced. In other words, the heater capacity is 5400W, the drying time is 92.48 minutes and the power consumption is 5.398kwh, while the heater capacity is 4150W, the drying time is 90.78 minutes and the power consumption is represented by 5.404kwh.

As a result, the temperature of the air can be lowered by reducing the amount of heat supplied to the air flowing into the drum 120 without frequently turning on or off the heater. This can prevent damage to the cloth and improve the stability of the dryer.

9 is a view showing an extract of the heat exchanger of Figure 2, Figure 10 is a graph showing the temperature and humidity of the humid air at the first point (①) and the third point (③) of Figure 9, Figure 11 is a view It is a graph comparing the dew point temperature of wet air at the 1st point (1) of 9 with the temperature of the water which exits a 1st heat exchanger. The thick arrows show the flow of wet air through the heat exchanger, and the thin arrows show the flow of water through the tube.

Referring to FIG. 9, the heat exchange part 200 may include a case 210 forming an accommodation space; At least one heat exchanger housed in the case 210; An air temperature sensor and a humidity sensor for calculating dew point temperature of the wet air passing through the heat exchanger; A water temperature sensor 251 for measuring a temperature of water flowing in the heat exchanger; And a quantity valve 240 for adjusting the amount of water flowing in the heat exchanger according to the calculated dew point temperature of the humid air.

At the bottom of the case 210, a drip tray (not shown) is formed to collect condensed water that is generated during the condensation process and is dropped.

The heat exchanger includes a first heat exchanger 220 and a second heat exchanger 230. Of course, the heat exchanger may be composed of one heat exchanger, if necessary, may be composed of three or more heat exchangers.

The first heat exchanger 220 is composed of a fin 221 and a tube 223, and condensed by the low temperature water to the high temperature and high humidity humid air exiting the drum 120 by the heat exchange method of air to water in a dry state Make it. The first heat exchanger 220 is installed on the left side of the case 210 (see FIG. 1) so as to be located at the outlet end of the circulation duct 114 (see FIG. 2) connected to the drum 120.

The fin 221 is a thin metal plate having excellent conductivity, and the plurality of thin plates are stacked such that the plurality of thin plates contact and pass vertically with hot and humid air at minute intervals from each other.

The tube 223 has low temperature (22 ° C.) water circulated therein and penetrates the pin 221 in a reciprocating manner.

Like the first heat exchanger 220, the second heat exchanger 230 includes a fin 231 and a tube 233, and dehumidified air exiting the first heat exchanger 220 by an air-to-water heat exchange method. Once again condensed with cold water to dry. The second heat exchanger 230 is installed on the right side of the case 210 to be located at the inlet end of the exhaust duct 161 (see FIG. 1).

The fin 231 is a thin metal plate having excellent conductivity, and the plurality of thin plates are stacked such that the plurality of thin plates contact and pass vertically with hot and humid air at minute intervals from each other.

The tube 233 has a low temperature (22 ° C.) of water circulating therein, and passes through the fin 231 in a reciprocating manner.

In addition, the tube 223 of the first heat exchanger 220 and the tube 233 of the second heat exchanger 230 are connected at an intermediate point of the first heat exchanger 220 and the second heat exchanger 230.

In addition, the inlet 233a of the tube 233 of the second heat exchanger 230 and the outlet 223a of the tube 223 of the first heat exchanger 220 are connected to an external water supply (not shown). It is connected to and receives water from the outside.

The water flowing into the inlet 233a of the tube 233 of the second heat exchanger 230 through the water hose passes through the water supply valve 240 and the tubes 233 and 223. 231 and the fin 221 of the first heat exchanger 220 are cooled, and then exit through the outlet 223a of the tube 223 of the first heat exchanger 220 to the water hose.

On the other hand, in order to dehumidify the humid air in the heat exchanger 200, it is necessary to grasp the state quantity of the humid air passing through the first heat exchanger 220 and the second heat exchanger 230.

That is, only the state amount of the wet air should be known to provide a suitable dew point temperature at which water can be condensed on the surfaces of the fins 221 of the first heat exchanger 220 and the fins 221 of the second heat exchanger 230 and the amount of water supply corresponding thereto. Can be adjusted.

There may be a number of factors that determine the amount of wet air condition, such as the temperature and humidity of the external air flowing into the heater or gas burner, the temperature of the tap water supplied to the heat exchanger, and the drying process according to the season The moisture content of the cloth in the drum changes during the process, and the temperature and humidity of the surrounding air where the dryer is installed.

Therefore, the inlet (hereinafter referred to as the first point ①) of the first heat exchanger 220 and all of the considerations between the first heat exchanger 220 and the second heat exchanger 230 (hereinafter referred to as the second point) (②)) and if the state of the wet air can be grasped at the outlet of the second heat exchanger 230 (hereinafter referred to as the third point ③), water consumption can be reduced by controlling the quantity through active control.

To this end, an air temperature sensor 253 and a humidity sensor 254 are installed at a first point ① and an air temperature sensor 255 and a humidity sensor 256 are installed at a second point ②. The air temperature sensor 257 and the humidity sensor 258 are installed at three points ③.

Referring to FIG. 10, RH_air_outlet represents the relative humidity of the humid air measured by the humidity sensor 258 at the third point ③, and RH_air_inlet is measured by the humidity sensor 254 at the first point ①. The relative humidity of the wet air is shown, T_air_inlet represents the temperature of the wet air measured by the air temperature sensor 253 at the first point ①, and the T_air_outlet is measured by the air temperature sensor 257 at the third point ③. The temperature of the wet air.

The temperature and humidity of the wet air measured by the air temperature sensors 253, 255, and 257 and the humidity sensors 254, 256, and 258 are output in volts, and the output values are pre-built in the microcomputer (not shown). It is calculated as the dew point temperature at the first point (①), the second point (②), and the third point (③) through the equation.

More specifically, the air temperature sensors 253, 255 and 257 and the humidity sensors 254, 256 and 258 are dry bulb temperature and wet bulb temperature (or relative humidity) at the first, second and third points in order to know the air quantity. Data is collected, and from the collected data, the microcomputer (not shown) calculates dew point temperatures at points 1, 2, and 3.

The water temperature sensor 251 is installed on the tubes (223, 233) exiting the first heat exchanger 220 and introduced into the second heat exchanger 230 to measure the temperature of the water flowing through the tubes (223, 233) do.

The water valve 240 is installed at the inlet 233a of the tube 233 passing through the second heat exchanger 230 to adjust the amount of water introduced into the tube 233. Of course, if necessary, it may be installed at the outlet 223a of the tube 223 passing through the first heat exchanger 220. At this time, the water valve 240 is an analog valve that can be opened and closed continuously and on or off (On / Off) two signals can be selected from a relatively inexpensive digital valve to open and close the water valve 240 have. For more precise control, a plurality of water valves 240 may be used.

9 and 11, since the temperature T_Hex1_Out_Surf of the water flowing through the tube 223 is lower than the dew point temperature T_Dew_In_Hex1 of the wet air at the first point ①, the entire fin 221 of the first exchanger 220 is lower. You can see that the condensation occurs evenly at Therefore, in this case, the water valve 240 is closed to prevent water from flowing into the tube 223 any more, thus reducing the amount of water used.

If the temperature of the water measured by the water temperature sensor 251 is higher than the calculated dew point temperature, the water supply valve 240 is opened to increase the amount of water supplied to the surface of the first heat exchanger 220 and the fin 221. The temperature of the surface of the fin 221 of the second heat exchanger 230 is lowered below the condensation temperature.

By the above-described configuration, the temperature of the surface of the fin 221 of the first heat exchanger 220 is maintained at a temperature lower than the dew point temperature of the wet air at the first point ① while controlling the amount of water used, and the second point ②. Maintaining the temperature of the fin surface of the second heat exchanger 230 below the dew point temperature of the wet air in the use of the heat exchanger while reducing the amount of water used.

On the other hand, it is possible to reduce the amount of water used in a simpler and less cost through the following method.

In the simplest method, when the dryer is cooled without any control, the amount of water used can be reduced by closing the water valve 240 completely.

Next, by directly receiving the temperature of the water supplied to the heat exchanger 200, it is also possible to adjust the amount of water used by adjusting the valve in several stages for each predetermined temperature range (calculated by experiment, etc. during product development). have.

Next, analyze the signal of the electrode sensor or humidity sensor used to determine the dryness of the existing dryer and discharge it to the outside of the dryer by intentionally reducing or stopping the quantity at the end of the drying, that is, when the graph starts to bend sharply. The amount of water used can be reduced while minimizing the damage of moisture.

According to the ductless dryer according to the embodiments of the present invention described above,

First, when the air volume decreases and the temperature value measured by the hot wind temperature sensor exceeds an appropriate temperature range, the gas valve is shut down in part or all to reduce or block the amount of gas flowing into the gas burner. As a result, the temperature of the air can be lowered by reducing the amount of heat supplied to the air flowing into the drum without frequently stopping the combustion of the gas, thereby preventing damage to the cloth and improving the stability of the dryer.

Second, when the air volume decreases and the temperature value measured by the hot wind temperature sensor exceeds the appropriate temperature range, the heater capacity is varied. Accordingly, the temperature of the air can be lowered by reducing the amount of heat supplied to the air flowing into the drum without frequently turning the heater on and off, thereby preventing damage to the fabric and improving the stability of the dryer.

Third, it is possible to maintain the temperature of the heat exchanger below the dew point temperature of the wet air while controlling the amount of water used, while reducing the amount of water used while maximizing the efficiency of the heat exchanger.

Claims (15)

main body; A drum rotatably installed on the main body; A hot air supply unit configured to provide hot air into the drum, and adjust heat for heating the air according to the air volume; And And a heat exchanger for dehumidifying the humid air exhausted from the drum. main body; A drum rotatably installed on the main body; Hot air supply unit for providing hot air into the drum; And And a heat exchanger to dehumidify the humid air exhausted from the drum and to adjust the amount of water for dehumidifying the humid air according to the dew point temperature of the humid air. main body; A drum rotatably installed on the main body; A hot air supply unit for providing hot air into the drum and adjusting heat for heating the air according to the air volume; And And a heat exchanger to dehumidify the humid air exhausted from the drum and to adjust the amount of water for dehumidifying the humid air according to the dew point temperature of the humid air. The method of claim 3, wherein the hot air supply unit, A gas combustor for mixing hot air with ignition to generate hot air; A gas valve for supplying and blocking gas to the gas burner; A hot air supply duct for directing hot air generated by the gas burner to the drum; And Ductless dryer comprising; at least one hot air temperature sensor for measuring the temperature of the hot air flowing into the drum. The ductless dryer of claim 4, wherein the gas valve is a solenoid valve. The method of claim 4, wherein the hot air supply unit, Multiple fixed heaters A hot air supply duct for directing hot air generated by the fixed heaters to the drum; And Ductless dryer comprising; at least one hot air temperature sensor for measuring the temperature of the hot air flowing into the drum. The method of claim 4, wherein the hot air supply unit, Fixed heater; At least one variable heater; Hot air supply duct for inducing hot air generated by the fixed heater and the variable heater to the drum; And Ductless dryer comprising; at least one hot air temperature sensor for measuring the temperature of the hot air flowing into the drum. The hot air temperature sensor according to any one of claims 4 to 7, Ductless dryer provided in the connection portion of the hot air supply duct and the drum. The method of claim 3, wherein the heat exchange unit, heat transmitter; An air temperature sensor and a humidity sensor for calculating dew point temperatures of the wet air passing through the heat exchanger; A water temperature sensor measuring a temperature of water flowing in the heat exchanger; And Ductless dryer comprising; a quantity valve for controlling the amount of water flowing in the heat exchanger according to the dew point temperature and the temperature of the water of the wet air. The method of claim 9, wherein the heat exchanger, A first heat exchanger; And Ductless dryer comprising; a second heat exchanger is arranged to enter the air exiting the first heat exchanger. The ductless dryer of claim 10, wherein the air temperature sensor is installed at least one of an inlet of the first heat exchanger, between the first heat exchanger and the second heat exchanger, and at least one outlet of the second heat exchanger. The ductless dryer of claim 10, wherein the humidity sensor is installed at at least one of an inlet of the first heat exchanger, between the first heat exchanger and the second heat exchanger, and an outlet of the second heat exchanger. The method of claim 10, And the first heat exchanger and the second heat exchanger include a plurality of fins and a tube passing therethrough, wherein the water temperature sensor measures a temperature of water flowing through the tube. The method according to any one of claims 9 to 13, The water quantity valve is an analog valve or a digital valve ductless dryer. The method according to any one of claims 9 to 13, The quantity valve is a plurality of ductless dryer.

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